<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="utils/my.js"></script>
</head>
<body>

</body>
<script>
   // 1- call是属性Function.prototype下的一个函数
   // 2- call会调用上下文件对象（函数）
   function fn(a,b){
       console.log("fn",this,a,b);
       return 100;
   }
   fn.call(1,100,200);
   fn.call("abc");
   fn.call(false);
   fn.call([]);
   fn.call({});
   fn.call(function(){});
   fn.call(undefined);
   const result =  fn.call(null);
   console.log(result);
</script>
</html>